I’m looking for a word or a phrase that describes an unduly big action to solve a problem that otherwise could be solved with moderate efforts. For instance, you have a pending application in a government department, and you want it to be processed quickly. You have two influential friends: A and B. A has a good reputation in the department in question, and one call from him would expedite the process. B is a national figure, who has goodwill across departments, and is a much bigger name than A. What would I call my action of choosing to take B’s help, even if I know that A’s help would suffice.
Some examples come to mind. The one I use most frequently is
"You don't swat a fly with a sledgehammer."
And I do recall reading one in Robert Heinlein's sci-fi novel The Moon is a Harsh Mistress in which one of the characters says
"You don't spank a baby with an ax."
That sounds a bit over the top (I wouldn't spank a baby with anything, much less an ax) and makes me queasy. Which is why I use the fly/sledgehammer trope.